If you don't mind driving, pasture board is a little easier to find further out of town. I know there are some places around Union and Pacific that are relatively inexpensive. To get turnout space inside the city you are going to pay. If you just need something cheap, I've had my eye on this place: Boarding Your Horse
I have not seen it in person since I'm not going to be ready to move up there for at least 6 months, but I had it in mind at least until I get a few big girl job paychecks in the bank.